I've been researching again large reptiles of the Paleocene (66.0-56.0 Million Years ago) and Eocene (56.0-33.9 Million Years ago) eras recently and I've come across something interesting - the sudden emergence of giant sea snakes in the Eocene. The Paleocene did see some large snakes, including the largest known snake in the fossil record the Boa relative Titanoboa (which grew up to 12.8-14.3 m. (42-47 feet) in length). But the sudden appearance of large sea snakes like Palaeophis colossaeus (which grew up to 12.3 m. (40 feet) in length) during the Eocene perplexes me as I've been struggling to find any large (or at least fairly large) sea snakes from the Paleocene.
That is except one possible contender named Vialovophis from the late Paleocene as described in a Scientific Paper from 1997.
https://www.researchgate.net/profile/Alexander-Averianov/publication/235806050_Paleogene_Sea_Snakes_from_the_Eastern_Part_of_Tethys/links/5437db850cf2027cbb205006/Paleogene-Sea-Snakes-from-the-Eastern-Part-of-Tethys.pdf
I'm just a bit curious why this? Did these sea snakes evolve such gigantic sizes only during the Eocene and why?